An instant Guardian/ICM poll conducted immediately after the debate concludes that Darling won the debate by 56 per cent to 44 per cent.

21.50The debate is done; the spin begins

"Alex Salmond said it would be Bannockburn, it turned out to be his Waterloo," says a senior pro-UK figure. "Alistair won because of forensic questioning on the currency. Alex lost because he couldn’t answer the questions. This could be a decisive moment."

21.55 STV's presenter apologises for the problems some people faced while trying to stream the independence debate online.

STV spokesman: "We are receiving an unprecedented demand for the live stream of the debate. We have made each section of the programme available for immediate catch up on our referendum site, scotlanddecides.com."

21.45 DEBATE ENDS

21.40 CLOSING STATEMENTS

Alistair Darling goes first ...

"I want Scotland to prosper," Darling says, adding that he wants to "tear down" the barriers to increasing wealth and opportunities.

The independence vote is the "biggest single decision" that Scots will ever make, Darling adds. "We can have the best of both world," he says, attacking the "guess work, blind faith and crossed fingers" of the SNP.

Darling finishes: I don't want to see the future of our children "gambled away".

Firstly, Salmond says that "if we are independent we get the government we voted for" at every election. Secondly, Scotland is a rich nation with "abundant national resources". Thirdly, no one is better placed to govern Scotland than Scots.

Salmond finishes: Independence is a "vote for ambition over fear ... This is our moment; lets take it".

21.35 Heat of the clashes during that middle period has gone, replaced with a more even-tempered debate. Tuition fees and the cost of pensions come up.

Darling on pensions and SNP promises: I bet whatever the UK is offering, Salmond is offering more.

21.28 Spinners watch

Better Together, the pro-UK campaign, is sending its interpretation of the debate straight to journalists' mobiles in the press room.

A few snippets: "Salmond reduced to launching personal attacks on Alistair Darling"; "Alistair Darling devastating in questioning Alex Salmond"; "Really significant that the audience has turned on Salmond during debate".

21.15 The pair clash on banking. Darling says as chancellor he took the call when RBS was about to go bust. Salmond says the financial crash came on Darling's watch.

Darling points out that Salmond once wrote to Sir Fred Goodwin, the then-RBS boss, offering support over a takeover bid that backfired. The First Minister points out that Darling's party knighted him.

21.07 Part three of the debate begins – questions from the audience

21.00 There are reports on Twitter that some people outside Scotland are having technical difficulties streaming the debate. Nothing confirmed. If we get any official word we'll post it here.

20.55 Here is a direct snippet from Darling's opening statement

It is important that we make this decision on the answers and facts that we can depend upon. I want to see Scotland prosper I don’t want to see new barriers, new borders where none exist – I don’t want anything to get in the way of the jobs and security that we need in this country so let’s say with confidence, let’s say with pride, let’s say with optimism No Thanks to the risks of independence and lets say let’s have the best of both worlds not just for us but for generations to come.

20.50 On to more serious topics. The pair clash over an independent Scotland's position in the European Union. They dispute the views of Jean-Claude Juncker, president of the European Commission, on independence and debate how easy it would be to negotiate membership.

Salmond asks if Darling agrees with David Cameron and believes Scotland could be a successful independent country. Darling repeatedly fails to give a Yes / No answer, adding that he has always said small countries can go it alone.

Salmond says he feels like Jeremy Paxman grilling Michael Howard as he tries to get an answer. Darling's response? You are more Michael Howard than Jeremy Paxman.

20.44 It is now Salmond's turn to grill Darling

His first question: "Why does the No campaign call itself Project Fear?"

His second question: Would people in Scotland drive on the other side of the road after independence? [He is paraphrasing Andy Burnham, shadow health secretary] Darling says that was a joke.

His third question: Would Scotland be at more danger from space attacks after independence? [He is paraphrasing Lord (George) Robertson, former defence secretary.] Darling dismisses the line of questioning as trivial.

20.40 Darling continues to push Salmond for a "Plan B" on currency

He's going through potential backup options. Do you want to adopt the euro? No, says Salmond, adding that Darling once supported joining the euro.

Would you keep the pound without a central bank, through sterlingisation? Salmond repeats that keeping the pound after independence is in the "best interests" of both Scotland and the UK.

He also brings up a Guardian storyquoting an anonymous UK minister saying there would be a currency union after independence.

The pair finish with a clash over public spending.

20.33 First up Darling is grilling Salmond. He begins on the currency. [The SNP wants to keep the pound after independence; all three UK-wide parties have ruled that option out.]

After early exchanges, Salmond pulls out a transcript of a Darling appearance on Newsnight. He says it proves Darling believes sharing the pound after independence is "logical and desirable".

Darling says the quote has been taken out of context and asks the First Minister to consider "for a minute" that he might be wrong on sharing the pound.

Some heckles and boos increasingly coming from the crowd. Lively exchanges.

20.30 Second section of the debate – when the candidates grill each other – has begun

20.26 A couple of tricky questions from Bernard Ponsonby, the host.

Darling is asked to name two powers that the Scottish Parliament will be given if independence is rejected. He names income tax, but stalls when asked exactly what proportion would be devolved. [The three UK-wide parties are split on this point.]

Salmond is asked whether the SNP – the party he leads – would back more devolution if there is a No vote. When pushed, Salmond says his party in all circumstances will vote for more powers for Scotland.

20.23Darling gets the first laugh of the night. Discussing being governed by parties which people don't vote for – a reference to Westminster rule over Scotland – Darling points at Salmond and says: "I didn't vote for him, but I'm stuck with him."

20.20 Here is a direct snippet from Salmond's opening statement

For more than half of my life Scotland has been governed by parties we didn’t elect at Westminster. These governments have given us everything from the poll tax to the bedroom tax and now the same people, in their self-declared Project Fear, are telling this country that we can't run our own affairs.

My case this evening is this: no one, no one will do a better job of running Scotland than the people who live and work in this country. On the 18th of September we have the opportunity of a lifetime. We should seize that opportunity with both hands.

20.15 Darling gives opening statement

Darling says "it is not our patriotism that is at stake tonight" but the "future of our country". He says that for the love of country and family it is "sometimes best to say No".

"If we decided to leave there is no going back, there is no second chance," Darling says about the choice over independence. A vote to say "no thanks" is not a vote for "no change".

He adds that Salmond is either refusing to answer key questions on independence or doesn't know the answers.

20.10 Salmond gives opening statement

"Very few people" dispute the fact that Scotland could be an independent country, Salmond says. He adds that many countries in the Commonwealth and the European Union are smaller than Scotland. He says the question is not whether Scotland "could" be independent but "should" be.

Salmond brings up food banks, Trident – "Europe's largest concentration of weapons of mass destruction" – and Westminster rule. He says the vote on September 18 is the "opportunity of a lifetime" that should be seized with both hands.

20.09 DEBATE BEGINS

20.01 New poll shows pro-UK camp leading

Results of a specially commissioned Ipsos MORI poll on independence has been revealed. Of those Scots 'absolutely certain' to vote on independence, 54 per cent said No, 40 per cent said Yes and 6 per cent were undecided. The Yes vote was up four points on the last poll.

A clearer view might come when undecided voters are removed – that puts the No camp on 58 per cent, the Yes camp 42 per cent. In other words, the pro-UK campaign is ahead by 16 percentage points with just over six weeks to go.

The two-hour debate will be split into three sections. 1) Opening statements and initial questioning from Bernard Ponsonby, STV's political editor. Results from a new Ipsos-MORI poll on voting intentions will also be revealed.2) Cross examination, where both candidates are allowed to grill each other on independence.3) Questions from an audience of 350 voters, carefully selected to reflect a balance of political views. There will also be closing statement

Who will win? And will it even matter? We asked some of the top talking heads on Scottish independence for their view. Two went for Salmond, two for Darling. All four said it would not be a "game-changer".

Have a read of their full thoughts here. But here's a taster of what John McTernan, Tony Blair’s former political secretary, had to say.

Alistair Darling faces a formidable opponent in Salmond. He has been speaking and debating in Parliament consistently all his career and now has seven years under his belt as First Minister.

Salmond is a confident debater, a skilful and witty performer. Alistair is a strong performer in the Commons, but it's been four years since he was regularly debating there. Practice does make perfect.

19.30 Debate, the drinking game

For those of you looking for a way to get through two hours of independence chatter, the Guardian's pulled together a special drinking game.

19.15 Today's main news: All three UK party leaders have signed a statement promising the Scottish Parliament more powers. Simon Johnson, our Scottish political editor, has the story.

Scotland will be allowed to set its own levels of income tax and benefits if the country rejects independence, David Cameron, Ed Miliband and Nick Clegg will announce today in an unprecedented joint declaration before tonight’s television debate.

In what will be seen as an attempt to undermine Alex Salmond, the three party leaders have made a joint announcement promising more powers for Scotland if it votes No.

The Prime Minister, his deputy and the Labour leader joined their Scottish party leaders by adding their names to a document pledging further devolution if separation is rejected on Sept 18.

19.00 Good evening and welcome to The Telegraph's live blog on tonight's Scottish independence TV debate.

The wait is finally over. For something approaching two years, Alex Salmond and Alistair Darling have been circling each other. There have been barbed sound bites, controversial interviews and plenty of speeches. But the pair – the acknowledged leaders of the Yes and No campaigns – are yet to meet face-to-face in a public debate. Until tonight.

Partly that is down to David Cameron. The First Minister has repeatedly called on the Prime Minister to face him in a debate, a request which Cameron has consistently rejected. Then there was weeks of backstage wrangling over exactly when, where and how Salmond and Darling would meet. But finally, with a little over six weeks left before the vote, we have our fight.

The Scottish commentariat is understandably excited. It has been variously billed as one of the biggest moments in Salmond's political career and the most important televised debate in Scotland's history. There will be others – a rematch is penned in for August 25 on BBC and talks with Channel 4 and Sky continue. But this clash will set the tone for the campaign's final straight.

What is at stake? For Salmond, there is the chance to convert the tens of thousands of extra voters he needs to win independence on September 18. Polls consistently show the Yes side behind (by 12 percentage points according to the last poll of polls). As such, the Yes team are saying this is a chance to get their message across to a mass audience.

For Darling, a 'steady as she goes' performance would likely suit just fine. Private mutterings about his leadership of Better Together, the pro-UK campaign, which surfaced earlier this year have largely faded. The No side is ahead in the polls. Ending the debate standing without any major slips would, one suspects, be enough to keep his camp happy.